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// License Agreement
// For Open Source Computer Vision Library
//
// Copyright (C) 2010-2012, Institute Of Software Chinese Academy Of Science, all rights reserved.
// Copyright (C) 2010-2012, Advanced Micro Devices, Inc., all rights reserved.
// Copyright (C) 2010-2012, Multicoreware, Inc., all rights reserved.
// Third party copyrights are property of their respective owners.
//
// @Authors
// Niko Li, newlife20080214@gmail.com
// Jia Haipeng, jiahaipeng95@gmail.com
// Xu Pang, pangxu010@163.com
// Wenju He, wenju@multicorewareinc.com
// Redistribution and use in source and binary forms, with or without modification,
// are permitted provided that the following conditions are met:
//
// * Redistribution's of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
//
// * Redistribution's in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
//
// * The name of the copyright holders may not be used to endorse or promote products
// derived from this software without specific prior written permission.
//
// This software is provided by the copyright holders and contributors as is and
// any express or implied warranties, including, but not limited to, the implied
// warranties of merchantability and fitness for a particular purpose are disclaimed.
// In no event shall the Intel Corporation or contributors be liable for any direct,
// indirect, incidental, special, exemplary, or consequential damages
// (including, but not limited to, procurement of substitute goods or services;
// loss of use, data, or profits; or business interruption) however caused
// and on any theory of liability, whether in contract, strict liability,
// or tort (including negligence or otherwise) arising in any way out of
// the use of this software, even if advised of the possibility of such damage.
//
//
__kernel void calculate_histogram(__global const uchar * src, int src_step, int src_offset, int src_rows, int src_cols,
__global uchar * hist, int total)
{
int lid = get_local_id(0);
int id = get_global_id(0);
int gid = get_group_id(0);
__local int localhist[BINS];
for (int i = lid; i < BINS; i += WGS)
localhist[i] = 0;
barrier(CLK_LOCAL_MEM_FENCE);
for (int grain = HISTS_COUNT * WGS; id < total; id += grain)
{
int src_index = mad24(id / src_cols, src_step, src_offset + id % src_cols);
atomic_inc(localhist + (int)src[src_index]);
}
barrier(CLK_LOCAL_MEM_FENCE);
for (int i = lid; i < BINS; i += WGS)
*(__global int *)(hist + mad24(gid, BINS * (int)sizeof(int), i * (int)sizeof(int))) = localhist[i];
}
__kernel void merge_histogram(__global const int * ghist, __global int * hist)
{
int lid = get_local_id(0);
#pragma unroll
for (int i = lid; i < BINS; i += WGS)
hist[i] = 0;
barrier(CLK_LOCAL_MEM_FENCE);
#pragma unroll
for (int i = 0; i < HISTS_COUNT; ++i)
{
#pragma unroll
for (int j = lid; j < BINS; j += WGS)
hist[j] += ghist[mad24(i, BINS, j)];
barrier(CLK_LOCAL_MEM_FENCE);
}
}
__kernel void calcLUT(__global uchar * dst, __constant int * hist, int total)
{
int lid = get_local_id(0);
__local int sumhist[BINS];
__local float scale;
sumhist[lid] = hist[lid];
barrier(CLK_LOCAL_MEM_FENCE);
if (lid == 0)
{
int sum = 0, i = 0;
while (!sumhist[i])
++i;
if (total == sumhist[i])
{
scale = 1;
for (int j = 0; j < BINS; ++j)
sumhist[i] = i;
}
else
{
scale = 255.f / (total - sumhist[i]);
for (sumhist[i++] = 0; i < BINS; i++)
{
sum += sumhist[i];
sumhist[i] = sum;
}
}
}
barrier(CLK_LOCAL_MEM_FENCE);
#pragma unroll
for (int i = lid; i < BINS; i += WGS)
dst[i]= convert_uchar_sat_rte(convert_float(sumhist[i]) * scale);
}